Atmospheric Movement and Local Weather

4. Atmosphere – the gasses held to Earth by gravity; the most dense are held near the surface.

2. Air Pressure a measure of the weight of the atmosphere on a given area (barometric pressure). Measured with a barometer.

5. Barometer – instrument used to measure air pressure

26. Wind– a current of air moving from high pressure to low pressure areas

3. Anemometer – instrument used to measure wind speed

13. Humidity – amount of water vapor present (dissolved) in the air.

20. Psychrometer – instrument used to measure humidity in the air

21. Radiation– the emission of energy as electromagnetic waves

7. Conduction– the process by which heat is directly transmitted through a substance

8. Convection Currents – cyclical (circular) currents caused by density differences

MoreDirect Sun Hot 0 o Equator 30 o S 60 o S 90 o S 30 o N 60 o N

9. The Coriolis Effect – effect of Earth’s rotation on the path of air and water. Causes paths to curve.

Global Convection Cells

http://www. pbs. org/wgbh/nova/vanished/jetstr_five http://www.pbs.org/wgbh/nova/vanished/jetstr_five.html https://tinyurl.com/y9bectgk 14. Jet Stream – narrow bands of high speed wind high in the atmosphere. Moves west to east in Northern Hemisphere.

19. Prevailing Winds - global wind currents at mid-latitudes; mostly blows in one direction

1. Air Masses Bodies of air with about the same temperature and humidity throughout

18. Ocean Currents generated by wind, temperature and a continuous, directed movement of seawater generated by wind, temperature and salinity differences

A strong surface current in the Atlantic Ocean that causes warmer climate along the East coast of the US and in NW Europe 11.Gulf Stream

http://esminfo. prenhall http://esminfo.prenhall.com/science/geoanim ations/animations/26_NinoNina.html 10. El Nino – period when Pacific surface waters along South American are warmer than normal; impacts temperature and rainfall in U.S.

16. La Nina – period when surface waters in Pacific are unusually cool; impacts temperatures and rainfall in the U.S.

Why does the Earth have wind and ocean currents? Reflection Question

Variables Affecting Local Weather

When convection and winds cause air masses to move, they bump into one another. The area where two air masses meet is called a front. Most severe weather occurs near frontal boundaries. 25. Weather Fronts – area where two air masses with different temperatures and pressures meet.

6. Cold Front - Cold air meets warm air - Fast moving and stormy, severe weather is likely

Cold Front Symbol

24. Warm Front - Warm air meets cold air - Slow moving with less severe weather

Warm Front Symbol

Warm and cool air masses that are not strong enough to move one another Sits still for a long period of time 23. Stationary Front

Stationary Front Symbol

12. High Pressure— Cool air sinks, clockwise circulation, and has clear, sunny skies.

17. Low Pressure— Warm air rises, counter clockwise circulation, and has cloud formation and possible bad weather

Frontal Boundary Simulations http://www.phschool.com/atschool/phsciexp/acti ve_art/weather_fronts/ https://tinyurl.com/3mtupw5 Frontal Boundary Simulations

High and Low Pressure Circulation

Air pressure is measured with a barometer in millibars. Millibars are represented by connected lines of equal pressure. This is a lot like the topographic map lines. The closer together the lines are, the faster the wind speed. The farther apart the lines are, the slower the wind speed. Air Pressure and Wind

The Earth’s Insulator The Sun heats the water and land every day. Land heats up rapidly, but cools off rapidly. Desert Water heats up slowly, but cools off slowly. Swimming at night The heat retained by the oceans is what keeps our planet insulated. The Earth’s Insulator

The heating and cooling of water and land produces land breezes and sea breezes. High pressure moves toward low pressure, pushing the warm air upward. As warm air rises, cooler air moves in and replaces it. Land and Sea Breezes

15. Land Breeze– happens at night when the water is warm (low pressure) while the land is cool (high pressure)

22. Sea Breeze– happens during the day when the water is cool (high pressure) and the land is warm (low pressure)

Sea Breeze and Land Breeze Simulation http://www.classzone.com/books/earth_science /terc/content/visualizations/es1903/es1903pag e01.cfm?chapter_no=visualization https://tinyurl.com/y85vqmjw Sea Breeze and Land Breeze Simulation

How do global patterns of atmospheric movement affect local weather? Reflection Question